A method is already known from EP Patent No. 1,559,068 for manufacturing electronic modules which each include two insulating sheets defining the external faces thereof, at least one electronic element having an external surface that substantially touches one of the external surfaces of the electronic module and an electronic circuit arranged between the two insulating sheets and connected to the electronic element. This method provides the following steps:                providing at least a first insulating sheet including a window for housing the electronic element;        inserting the electronic instrument in the window of the first insulating sheet, the electronic element being provided with conductive connection pads arranged on an inner surface opposite to the external surface thereof;        superposing an adhesive protective film that extends at least into the area between the electronic element and the edges of the window, the protective film holding the electronic element in the window and closing any slit between the electronic element and the lateral wall of the window;        placing the electronic circuit in a zone close to the window and connecting the electronic element to the electronic circuit through a window provided or made in the protective film and located opposite the conductive connection paths;        depositing a filler material on the set of elements already provided and superposing a second insulating sheet on the filler material;        pressing or laminating the assembly produced by the preceding steps, the filler material forming a layer compensating for any surface contours resulting from assembling the electronic module.        
The manufacturing method described above solves an important problem, namely, preventing the filler material, generally formed by a resin which is in a viscous liquid state when pressure is applied to form the electronic module, from flowing into any slit between the electronic element and the lateral wall of the window in which it is arranged, so as to prevent the resin extending at least partially onto the visible external surface of the electronic element. However, the manufacturing method presents a problem in relation to the sequence of steps, in particular the fact that the electrical connection between the visible electronic element and the internal electronic unit is achieved once the electronic element has been inserted in a window in an external insulating layer of the card being manufactured and the adhesive protective layer is in place. This sequence of steps raises a practical problem given that card manufacturing equipments or facilities are not generally equipped with a device for welding or assembling various electronic units. Indeed, generally, the various electronic circuits and elements are first assembled to form electronic devices and then these electronic devices are taken to a conventional card manufacturing equipment or facility in which the various materials used to form the cards are provided and processed in an appropriate manner to obtain high quality electronic cards into which the electronic devices are respectively incorporated. The aforecited Patent of the prior art does not propose temporally separating production of the electronic devices from the manufacture of the cards incorporating these electronic devices. Although the method described in the aforecited document can be implemented and used to obtain complex electronic cards, it has a major drawback for those skilled in the art specialised in manufacturing finished electronic cards or inlets, who prefer to separate the production of the electronic devices from the card forming process.
It is an object of the present invention to overcome the major drawback of the prior art method mentioned above.